Inflammatory bowel disease is the term generally applied to two diseases, namely ulcerative colitis and Crohn's disease.
Ulcerative colitis is a chronic inflammatory disease of unknown aetiology afflicting only the large bowel and, except when very severe, limited to the bowel mucosa. The course of the disease may be continuous or relapsing, mild or severe. It is curable by total colectomy which may be needed for acute severe disease or chronic unremitting disease. Most patients with ulcerative colitis are managed medically rather than surgically.
Crohn's disease is also a chronic inflammatory disease of unknown aetiology but, unlike ulcerative colitis, it can affect any part of the bowel. Although lesions may start superficially, the inflammatory process extends through the bowel wall to the draining lymph nodes. As with ulcerative colitis, the course of the disease may be continuous or relapsing, mild or severe but, unlike ulcerative colitis it is not curable by resection of the involved segment of bowel. Most patients with Crohn's disease come to surgery at some time, but subsequent relapse is common and continuous medical treatment is usual.
For treatment of acute attacks of ulcerative colitis, glucocorticosteroids such as prednisone or prednisolone acetate are almost invariably used and given by mouth for the average acute attack or relapse, or locally, by enema.
After remission has been achieved, sulphasalazine is the maintenance treatment of choice in treating ulcerative colitis. This drug, however, has a significant number of side effects chiefly due to absorption of the sulphapyridine moiety from the colon. Recently compounds which contain only 5-aminosalicylic acid have been developed; these are as effective as sulphasalazine and do not have the sulphapyridine side effects but do have side effects of their own, notably diarrhoea.
Glucocorticosteroids are, however, not used for maintenance of remission in ulcerative colitis; doses that do not produce unacceptable side effects are ineffective, and patients who need chronic high dose glucocorticosteroids for control of their disease almost invariably are treated by colectomy.
As with ulcerative colitis, glucocorticosteroids are the treatment of choice for severe active Crohn's disease, but ideally only to achieve remission, after which they should be stopped. However, all too frequently the disease does not satisfactorily remit, and glucocorticosteroids may be necessary to maintain control of symptoms. Sulphasalazine is also useful in less severe cases, particularly for disease involving the colon.
Very often in Crohn's disease, however, primary medical treatment of the disease process is ineffective, and only symptomatic treatment is of value i.e. analgesics for pain and opiates for diarrhoea. Most patients eventually require surgery.